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[Qemu-devel] [RESEND PATCH] target/arm: change arch timer registers access permission

gengdongjiu posted 1 patch 6 years, 8 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/1552292963-19430-1-git-send-email-gengdongjiu@huawei.com
Maintainers: Peter Maydell <peter.maydell@linaro.org>
There is a newer version of this series
target/arm/helper.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)
[Qemu-devel] [RESEND PATCH] target/arm: change arch timer registers access permission
Posted by gengdongjiu 6 years, 8 months ago 
From: Dongjiu Geng <gengdongjiu@huawei.com>

Some generic arch timer registers are Config-RW in the EL0,
which means the EL0 exception level can have write permission
if it is appropriately configured.

When VM access registers, it firstly checks whether they have RW
permission, then check whether it is appropriately configured.
If they are defined to Ready only in EL0, even though they have been
appropriately configured, they still do not have write permission.
So need to add the write permission according to ARMV8 spec when
define it.

Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
---
When kernel or Hypervisor configures the timer registers to RW in EL0
user space, it will still have below panic when EL0 user space access
the timer registers.

[INFO ]@(el0_sync:60): UNIMPLEMENTED, esr=2000000
[INFO ]@(unimpl_exception:88): KERNEL UNIMPLEMENTED EXCEPTION
[INFO ]@(unimpl_exception:98): FAR=0000000000000000, ESR=02000000 (EC=0x0, IL=0x1, ISS=0x0)
[INFO ]@(dump_registers:64): KERNEL REGISTERS
[INFO ]@(dump_registers:68): X0=00000000f52b7d50 X1=00000000040d5040
[INFO ]@(dump_registers:68): X2=0000004000033e10 X3=0000000000000000
[INFO ]@(dump_registers:68): X4=000000007fffffff X5=0000000000000020
[INFO ]@(dump_registers:68): X6=0000000000000020 X7=000000000c00b030
---
 target/arm/helper.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 2607d39..3db94c6 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -2665,7 +2665,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     /* per-timer control */
     { .name = "CNTP_CTL", .cp = 15, .crn = 14, .crm = 2, .opc1 = 0, .opc2 = 1,
       .secure = ARM_CP_SECSTATE_NS,
-      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access,
       .fieldoffset = offsetoflow32(CPUARMState,
                                    cp15.c14_timer[GTIMER_PHYS].ctl),
@@ -2674,7 +2674,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     { .name = "CNTP_CTL_S",
       .cp = 15, .crn = 14, .crm = 2, .opc1 = 0, .opc2 = 1,
       .secure = ARM_CP_SECSTATE_S,
-      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access,
       .fieldoffset = offsetoflow32(CPUARMState,
                                    cp15.c14_timer[GTIMER_SEC].ctl),
@@ -2682,14 +2682,14 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     },
     { .name = "CNTP_CTL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 2, .opc2 = 1,
-      .type = ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_PHYS].ctl),
       .resetvalue = 0,
       .writefn = gt_phys_ctl_write, .raw_writefn = raw_write,
     },
     { .name = "CNTV_CTL", .cp = 15, .crn = 14, .crm = 3, .opc1 = 0, .opc2 = 1,
-      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_RW,
       .accessfn = gt_vtimer_access,
       .fieldoffset = offsetoflow32(CPUARMState,
                                    cp15.c14_timer[GTIMER_VIRT].ctl),
@@ -2697,7 +2697,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     },
     { .name = "CNTV_CTL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 3, .opc2 = 1,
-      .type = ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_vtimer_access,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_VIRT].ctl),
       .resetvalue = 0,
@@ -2706,31 +2706,31 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     /* TimerValue views: a 32 bit downcounting view of the underlying state */
     { .name = "CNTP_TVAL", .cp = 15, .crn = 14, .crm = 2, .opc1 = 0, .opc2 = 0,
       .secure = ARM_CP_SECSTATE_NS,
-      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access,
       .readfn = gt_phys_tval_read, .writefn = gt_phys_tval_write,
     },
     { .name = "CNTP_TVAL_S",
       .cp = 15, .crn = 14, .crm = 2, .opc1 = 0, .opc2 = 0,
       .secure = ARM_CP_SECSTATE_S,
-      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access,
       .readfn = gt_sec_tval_read, .writefn = gt_sec_tval_write,
     },
     { .name = "CNTP_TVAL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 2, .opc2 = 0,
-      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_ptimer_access, .resetfn = gt_phys_timer_reset,
       .readfn = gt_phys_tval_read, .writefn = gt_phys_tval_write,
     },
     { .name = "CNTV_TVAL", .cp = 15, .crn = 14, .crm = 3, .opc1 = 0, .opc2 = 0,
-      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_vtimer_access,
       .readfn = gt_virt_tval_read, .writefn = gt_virt_tval_write,
     },
     { .name = "CNTV_TVAL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 3, .opc2 = 0,
-      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_R,
+      .type = ARM_CP_NO_RAW | ARM_CP_IO, .access = PL1_RW | PL0_RW,
       .accessfn = gt_vtimer_access, .resetfn = gt_virt_timer_reset,
       .readfn = gt_virt_tval_read, .writefn = gt_virt_tval_write,
     },
@@ -2758,7 +2758,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     /* Comparison value, indicating when the timer goes off */
     { .name = "CNTP_CVAL", .cp = 15, .crm = 14, .opc1 = 2,
       .secure = ARM_CP_SECSTATE_NS,
-      .access = PL1_RW | PL0_R,
+      .access = PL1_RW | PL0_RW,
       .type = ARM_CP_64BIT | ARM_CP_IO | ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_PHYS].cval),
       .accessfn = gt_ptimer_access,
@@ -2766,7 +2766,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     },
     { .name = "CNTP_CVAL_S", .cp = 15, .crm = 14, .opc1 = 2,
       .secure = ARM_CP_SECSTATE_S,
-      .access = PL1_RW | PL0_R,
+      .access = PL1_RW | PL0_RW,
       .type = ARM_CP_64BIT | ARM_CP_IO | ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_SEC].cval),
       .accessfn = gt_ptimer_access,
@@ -2774,14 +2774,14 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     },
     { .name = "CNTP_CVAL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 2, .opc2 = 2,
-      .access = PL1_RW | PL0_R,
+      .access = PL1_RW | PL0_RW,
       .type = ARM_CP_IO,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_PHYS].cval),
       .resetvalue = 0, .accessfn = gt_ptimer_access,
       .writefn = gt_phys_cval_write, .raw_writefn = raw_write,
     },
     { .name = "CNTV_CVAL", .cp = 15, .crm = 14, .opc1 = 3,
-      .access = PL1_RW | PL0_R,
+      .access = PL1_RW | PL0_RW,
       .type = ARM_CP_64BIT | ARM_CP_IO | ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_VIRT].cval),
       .accessfn = gt_vtimer_access,
@@ -2789,7 +2789,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     },
     { .name = "CNTV_CVAL_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 3, .opc2 = 2,
-      .access = PL1_RW | PL0_R,
+      .access = PL1_RW | PL0_RW,
       .type = ARM_CP_IO,
       .fieldoffset = offsetof(CPUARMState, cp15.c14_timer[GTIMER_VIRT].cval),
       .resetvalue = 0, .accessfn = gt_vtimer_access,
-- 
2.7.4
Re: [Qemu-devel] [RESEND PATCH] target/arm: change arch timer registers access permission
Posted by Peter Maydell 6 years, 8 months ago 
On Mon, 11 Mar 2019 at 08:29, gengdongjiu <gengdongjiu@huawei.com> wrote:
>
> From: Dongjiu Geng <gengdongjiu@huawei.com>
>
> Some generic arch timer registers are Config-RW in the EL0,
> which means the EL0 exception level can have write permission
> if it is appropriately configured.
>
> When VM access registers, it firstly checks whether they have RW
> permission, then check whether it is appropriately configured.
> If they are defined to Ready only in EL0, even though they have been

"read only" ?

> appropriately configured, they still do not have write permission.
> So need to add the write permission according to ARMV8 spec when
> define it.
>
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>

Yes, this seems to be a bug which has been present since
I added the generic timer support in commit 55d284af8e31b in 2013.

I'm not sure why the bug is there -- my best guess is that I
incorrectly copied the permission flags from the CNTFRQ register
(which really is RO from PL0 but RW from PL1 and above) to
these other registers which should be fully RW from PL0.

> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 2607d39..3db94c6 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -2665,7 +2665,7 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
>      /* per-timer control */
>      { .name = "CNTP_CTL", .cp = 15, .crn = 14, .crm = 2, .opc1 = 0, .opc2 = 1,
>        .secure = ARM_CP_SECSTATE_NS,
> -      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_R,
> +      .type = ARM_CP_IO | ARM_CP_ALIAS, .access = PL1_RW | PL0_RW,

The PLx_{R,W,RW} constants all imply access is also possible from
the higher PLs, so this can just be written ".access = PL0_RW".

thanks
-- PMM

Patchew 2.1-devel-b67e4c2

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